1. Field of the Invention
The present invention relates generally to a catheter based system for treating a remote location within a patient and more particularly to the hand-held actuator devices of stent delivery systems.
2. Background
A delivery system for a self-expanding stent usually has the stent distally adjacent to a tube, both within a sleeve at the distal end of a catheter. To deliver the stent, the sleeve has to be pulled back while the tube holds the stent from moving back with the sleeve. Therefore, the tube is placed adjacent to the stent and acts as a barrier and restrains the stent from moving while the sleeve is pulled back.
WO 02/087470 discloses a hand device for a catheter stent delivering system. The hand device can be operated one-handed to ease the operation with such a device. The main function such devices have to include are:                1) to pull back the sleeve, for example by pulling a wire which is connected to the proximal end of the outer sleeve;        2) to restrain simultaneously the inner tube from being pulled back together with the sleeve; and        3) to provide a visual signal of how much length of the sleeve has already been pulled back        
The restraint function can be performed by a hub that is mounted within the hand-held actuator and itself receives the proximal end of the tube. To pull the wire, in WO 02/087470 is provided an index-finger-triggering-system, which causes a mechanical apparatus within the device to pull in the wire and draw the proximal end of the sleeve into the housing of the hand unit. A disadvantage of the index-finger-triggering-system is that it is a pistol-like device and the impression it gives to the operator, of direct tactile feedback about the progress of stent release, some operators might find unconvincing. Furthermore, the maximum length of wire, which can be reeled in by successive squeezes of the trigger, is defined by the length of the, track in the hand unit along which the proximal end of the sleeve advances proximally, rendering it incapable of releasing a self-expanding stent which is longer than the track.
EP 1 299 050 discloses a thumb-actuating-screwing-system, but this has all disadvantages of the index-finger-triggering-system. In addition the thumb has to be lifted between every turn of the screw, which makes the control of the pull-mechanism less comfortable.
Both of the above identified systems have a component protruding from the housing of the hand unit, which moves proximally through the device with the catheter being withdrawn, and so acts as a distance indicator. When the operator starts coiling-up the wire, the indicator moves and the operator and his or her assistants can judge the extent of the progressive stent release from the distance the indicator has travelled proximally along the length of the housing of the hand unit.
Stents are getting longer (e.g. in a leg the stent can be about 30 cm). It is one object of the present invention to provide a hand-held actuator for release of a self-expanding stent with a length longer than can be handled by the known hand-held actuators.
Generally, the present invention aims to improve on the performance of the devices of WO 02/087470 and EP 1 299 050, in the respects mentioned above.